Abstract The goal of this study is to provide a comprehensive evaluation of the U.S. Housing and Urban Development's (HUDs) smoke-free public housing rule, effective August 3, 2018, in the District of Columbia Housing Authority. The rule prohibits lit tobacco products and hookah use in all living units, common areas, administrative office buildings, and outdoor areas up to 25 feet in all public housing facilities. A primary goal of the rule is to create healthier homes for families living in public housing. Tobacco use control laws that prohibit smoking in public places have helped reduce smoking prevalence by 40% and exposure of nonsmokers to secondhand smoke by 71%. Even with declines in these indicators for the general population, progress has been considerably slower for low-income, racial and ethnic minorities who experience disproportionate harm from smoking and secondhand smoke exposure. Homes remain a significant source of SHSe due, in part, to the substantial amount of time adults and children spend in the home. SHSe is particularly problematic in multiunit housing, where secondhand smoke can enter non-smoking units through ventilation systems and other means. While a few studies suggest positive effects of smoke-free public housing on indoor air quality, SHSe, and smoking cessation, limitations exist. Namely, longitudinal studies with more than one post-intervention assessment, studies evaluating the effect on short- and long-term health outcomes, and studies that include objective measures of secondhand smoke exposure are needed. This study addresses the methodological limitations of current evaluation studies and is designed to evaluate the effect of HUDs rule specifically. A qualitative approach will be used to document the implementation process of the rule. A quantitative approach will be used to evaluate the effects of the rule on SHSe and health outcomes of adults and children. The evaluation will include three cohorts: a cohort of residences to assess the effect of HUDs policy on SHSe, a cohort of smoking adults to assess effects of the rule on smoking behavior, and a cohort of youth with asthma to assess effects of the rule on children's respiratory health. Baseline data collection will occur prior to August 2018, and funding from the proposed study will be used for four post-implementation assessments (up to 24-months post rule). Differential effects of the rule will be examined across family and senior/disabled communities. Evaluating this rule is critical, given that over 2 million public housing residents will be effected and the potential for this rule to reduce tobacco-related health disparities. Processes found to be effective in the current study have the potential to accelerate the implementation of tobacco control policies in the future.